Abstract

Previous studies of unimodal (spoken–spoken) language switching have often found longer reaction times and higher error rates in switch trials than in repeat trials, particularly for unbalanced bilinguals. Studies of hearing signers (bimodal bilinguals) have found that they often produce ‘code-blends’ rather than sequential code-switches; such simultaneous production is generally not possible in unimodal utterances. The present study explored sequential language switching and simultaneous language production (dual-task) in bimodal bilinguals. The Methodological Experiment adapted the language-switching paradigm, used previously to test unimodal language switching, to bimodal data and required significant methodological development. The Methodological Experiment and Experiment 1 examined modality effects in language switching with two Modalities: unimodal (German–English) and bimodal (German–DGS). Reaction times were shorter, error rates lower and switch costs smaller in bimodal switching blocks than in unimodal blocks, indicating a bimodal language switching advantage. Experiment 2 examined simultaneous bimodal language production, comparing dual-task and single-task trials in order to determine whether there are dual-task advantages. Previous studies found dual-task costs, or in some cases, no dual-task cost and no advantage, for responses across modalities in non-language tasks. However, our results show that in a bimodal bilingual switching condition, there can be a dual-task advantage, especially when switching into a dual-task trial (code-blend). We suggest that language is different from other task components in task-switching and dual-task studies and that a code-blend forms a unit which is greater than the sum of its parts.